Commit Graph

14323 Commits

Author SHA1 Message Date
Linus Torvalds
54d1ae492f Merge branch 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux
Pull module signing fixes from Rusty Russell:
 "David gave me these a month ago, during my git workflow churn :("

* 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux:
  ASN.1: Fix an indefinite length skip error
  MODSIGN: Don't use enum-type bitfields in module signature info block
2012-12-06 08:29:08 -08:00
Linus Torvalds
cfd1f032f9 Merge branch 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull watchdog fix from Thomas Gleixner:
 "Trivial CPU hotplug regression fix for the watchdog code"

* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  watchdog: Fix CPU hotplug regression
2012-12-06 08:27:11 -08:00
David Howells
12e130b045 MODSIGN: Don't use enum-type bitfields in module signature info block
Don't use enum-type bitfields in the module signature info block as we can't be
certain how the compiler will handle them.  As I understand it, it is arch
dependent, and it is possible for the compiler to rearrange them based on
endianness and to insert a byte of padding to pad the three enums out to four
bytes.

Instead use u8 fields for these, which the compiler should emit in the right
order without padding.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2012-12-05 11:27:24 +10:30
Thomas Gleixner
8d4516904b watchdog: Fix CPU hotplug regression
Norbert reported:
"3.7-rc6 booted with nmi_watchdog=0 fails to suspend to RAM or
 offline CPUs. It's reproducable with a KVM guest and physical
 system."

The reason is that commit bcd951cf(watchdog: Use hotplug thread
infrastructure) missed to take this into account. So the cpu offline
code gets stuck in the teardown function because it accesses non
initialized data structures.

Add a check for watchdog_enabled into that path to cure the issue.

Reported-and-tested-by: Norbert Warmuth <nwarmuth@t-online.de>
Tested-by: Joseph Salisbury <joseph.salisbury@canonical.com>
Link: http://lkml.kernel.org/r/alpine.LFD.2.02.1211231033230.2701@ionos
Link: http://bugs.launchpad.net/bugs/1079534
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2012-12-04 19:56:59 +01:00
Linus Torvalds
df2fc246c8 Merge branch 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux
Pull module fixes from Rusty Russell:
 "Module signing build fixes for blackfin and metag"

* 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux:
  modsign: add symbol prefix to certificate list
  linux/kernel.h: define SYMBOL_PREFIX
2012-12-04 09:32:12 -08:00
Linus Torvalds
ca50496eb4 Merge branch 'for-3.7-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq
Pull workqueue fixes from Tejun Heo:
 "So, safe fixes my ass.

  Commit 8852aac25e ("workqueue: mod_delayed_work_on() shouldn't queue
  timer on 0 delay") had the side-effect of performing delayed_work
  sanity checks even when @delay is 0, which should be fine for any sane
  use cases.

  Unfortunately, megaraid was being overly ingenious.  It seemingly
  wanted to use cancel_delayed_work_sync() before cancel_work_sync() was
  introduced, but didn't want to waste the space for full delayed_work
  as it was only going to use 0 @delay.  So, it only allocated space for
  struct work_struct and then cast it to struct delayed_work and passed
  it into delayed_work functions - truly awesome engineering tradeoff to
  save some bytes.

  Xiaotian fixed it by making megraid allocate full delayed_work for
  now.  It should be converted to use work_struct and cancel_work_sync()
  but I think we better do that after 3.7.

  I added another commit to change BUG_ON()s in __queue_delayed_work()
  to WARN_ON_ONCE()s so that the kernel doesn't crash even if there are
  more such abuses."

* 'for-3.7-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
  workqueue: convert BUG_ON()s in __queue_delayed_work() to WARN_ON_ONCE()s
  megaraid: fix BUG_ON() from incorrect use of delayed work
2012-12-04 09:02:45 -08:00
Tejun Heo
fc4b514f27 workqueue: convert BUG_ON()s in __queue_delayed_work() to WARN_ON_ONCE()s
8852aac25e ("workqueue: mod_delayed_work_on() shouldn't queue timer on
0 delay") unexpectedly uncovered a very nasty abuse of delayed_work in
megaraid - it allocated work_struct, casted it to delayed_work and
then pass that into queue_delayed_work().

Previously, this was okay because 0 @delay short-circuited to
queue_work() before doing anything with delayed_work.  8852aac25e
moved 0 @delay test into __queue_delayed_work() after sanity check on
delayed_work making megaraid trigger BUG_ON().

Although megaraid is already fixed by c1d390d8e6 ("megaraid: fix
BUG_ON() from incorrect use of delayed work"), this patch converts
BUG_ON()s in __queue_delayed_work() to WARN_ON_ONCE()s so that such
abusers, if there are more, trigger warning but don't crash the
machine.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Xiaotian Feng <xtfeng@gmail.com>
2012-12-04 07:58:47 -08:00
Mike Galbraith
fd8ef11730 Revert "sched, autogroup: Stop going ahead if autogroup is disabled"
This reverts commit 800d4d30c8.

Between commits 8323f26ce3 ("sched: Fix race in task_group()") and
800d4d30c8 ("sched, autogroup: Stop going ahead if autogroup is
disabled"), autogroup is a wreck.

With both applied, all you have to do to crash a box is disable
autogroup during boot up, then reboot..  boom, NULL pointer dereference
due to commit 800d4d30c8 not allowing autogroup to move things, and
commit 8323f26ce3 making that the only way to switch runqueues:

  BUG: unable to handle kernel NULL pointer dereference at           (null)
  IP: [<ffffffff81063ac0>] effective_load.isra.43+0x50/0x90
  Pid: 7047, comm: systemd-user-se Not tainted 3.6.8-smp #7 MEDIONPC MS-7502/MS-7502
  RIP: effective_load.isra.43+0x50/0x90
  Process systemd-user-se (pid: 7047, threadinfo ffff880221dde000, task ffff88022618b3a0)
  Call Trace:
    select_task_rq_fair+0x255/0x780
    try_to_wake_up+0x156/0x2c0
    wake_up_state+0xb/0x10
    signal_wake_up+0x28/0x40
    complete_signal+0x1d6/0x250
    __send_signal+0x170/0x310
    send_signal+0x40/0x80
    do_send_sig_info+0x47/0x90
    group_send_sig_info+0x4a/0x70
    kill_pid_info+0x3a/0x60
    sys_kill+0x97/0x1a0
    ? vfs_read+0x120/0x160
    ? sys_read+0x45/0x90
    system_call_fastpath+0x16/0x1b
  Code: 49 0f af 41 50 31 d2 49 f7 f0 48 83 f8 01 48 0f 46 c6 48 2b 07 48 8b bf 40 01 00 00 48 85 ff 74 3a 45 31 c0 48 8b 8f 50 01 00 00 <48> 8b 11 4c 8b 89 80 00 00 00 49 89 d2 48 01 d0 45 8b 59 58 4c
  RIP  [<ffffffff81063ac0>] effective_load.isra.43+0x50/0x90
   RSP <ffff880221ddfbd8>
  CR2: 0000000000000000

Signed-off-by: Mike Galbraith <efault@gmx.de>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Yong Zhang <yong.zhang0@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: stable@vger.kernel.org # 2.6.39+
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-12-03 11:10:24 -08:00
James Hogan
84ecfd15f5 modsign: add symbol prefix to certificate list
Add the arch symbol prefix (if applicable) to the asm definition of
modsign_certificate_list and modsign_certificate_list_end. This uses the
recently defined SYMBOL_PREFIX which is derived from
CONFIG_SYMBOL_PREFIX.

This fixes the build of module signing on the blackfin and metag
architectures.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: David Howells <dhowells@redhat.com>
Cc: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2012-12-03 13:06:25 +10:30
Tejun Heo
8852aac25e workqueue: mod_delayed_work_on() shouldn't queue timer on 0 delay
8376fe22c7 ("workqueue: implement mod_delayed_work[_on]()")
implemented mod_delayed_work[_on]() using the improved
try_to_grab_pending().  The function is later used, among others, to
replace [__]candel_delayed_work() + queue_delayed_work() combinations.

Unfortunately, a delayed_work item w/ zero @delay is handled slightly
differently by mod_delayed_work_on() compared to
queue_delayed_work_on().  The latter skips timer altogether and
directly queues it using queue_work_on() while the former schedules
timer which will expire on the closest tick.  This means, when @delay
is zero, that [__]cancel_delayed_work() + queue_delayed_work_on()
makes the target item immediately executable while
mod_delayed_work_on() may induce delay of upto a full tick.

This somewhat subtle difference breaks some of the converted users.
e.g. block queue plugging uses delayed_work for deferred processing
and uses mod_delayed_work_on() when the queue needs to be immediately
unplugged.  The above problem manifested as noticeably higher number
of context switches under certain circumstances.

The difference in behavior was caused by missing special case handling
for 0 delay in mod_delayed_work_on() compared to
queue_delayed_work_on().  Joonsoo Kim posted a patch to add it -
("workqueue: optimize mod_delayed_work_on() when @delay == 0")[1].
The patch was queued for 3.8 but it was described as optimization and
I missed that it was a correctness issue.

As both queue_delayed_work_on() and mod_delayed_work_on() use
__queue_delayed_work() for queueing, it seems that the better approach
is to move the 0 delay special handling to the function instead of
duplicating it in mod_delayed_work_on().

Fix the problem by moving 0 delay special case handling from
queue_delayed_work_on() to __queue_delayed_work().  This replaces
Joonsoo's patch.

[1] http://thread.gmane.org/gmane.linux.kernel/1379011/focus=1379012

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-and-tested-by: Anders Kaseorg <andersk@MIT.EDU>
Reported-and-tested-by: Zlatko Calusic <zlatko.calusic@iskon.hr>
LKML-Reference: <alpine.DEB.2.00.1211280953350.26602@dr-wily.mit.edu>
LKML-Reference: <50A78AA9.5040904@iskon.hr>
Cc: Joonsoo Kim <js1304@gmail.com>
2012-12-01 16:43:18 -08:00
Mike Galbraith
412d32e6c9 workqueue: exit rescuer_thread() as TASK_RUNNING
A rescue thread exiting TASK_INTERRUPTIBLE can lead to a task scheduling
off, never to be seen again.  In the case where this occurred, an exiting
thread hit reiserfs homebrew conditional resched while holding a mutex,
bringing the box to its knees.

PID: 18105  TASK: ffff8807fd412180  CPU: 5   COMMAND: "kdmflush"
 #0 [ffff8808157e7670] schedule at ffffffff8143f489
 #1 [ffff8808157e77b8] reiserfs_get_block at ffffffffa038ab2d [reiserfs]
 #2 [ffff8808157e79a8] __block_write_begin at ffffffff8117fb14
 #3 [ffff8808157e7a98] reiserfs_write_begin at ffffffffa0388695 [reiserfs]
 #4 [ffff8808157e7ad8] generic_perform_write at ffffffff810ee9e2
 #5 [ffff8808157e7b58] generic_file_buffered_write at ffffffff810eeb41
 #6 [ffff8808157e7ba8] __generic_file_aio_write at ffffffff810f1a3a
 #7 [ffff8808157e7c58] generic_file_aio_write at ffffffff810f1c88
 #8 [ffff8808157e7cc8] do_sync_write at ffffffff8114f850
 #9 [ffff8808157e7dd8] do_acct_process at ffffffff810a268f
    [exception RIP: kernel_thread_helper]
    RIP: ffffffff8144a5c0  RSP: ffff8808157e7f58  RFLAGS: 00000202
    RAX: 0000000000000000  RBX: 0000000000000000  RCX: 0000000000000000
    RDX: 0000000000000000  RSI: ffffffff8107af60  RDI: ffff8803ee491d18
    RBP: 0000000000000000   R8: 0000000000000000   R9: 0000000000000000
    R10: 0000000000000000  R11: 0000000000000000  R12: 0000000000000000
    R13: 0000000000000000  R14: 0000000000000000  R15: 0000000000000000
    ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0018

Signed-off-by: Mike Galbraith <mgalbraith@suse.de>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: stable@vger.kernel.org
2012-12-01 15:56:42 -08:00
Linus Torvalds
455e987c0c Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull perf fixes from Ingo Molnar:
 "This is mostly about unbreaking architectures that took the UAPI
  changes in the v3.7 cycle, plus misc fixes."

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf kvm: Fix building perf kvm on non x86 arches
  perf kvm: Rename perf_kvm to perf_kvm_stat
  perf: Make perf build for x86 with UAPI disintegration applied
  perf powerpc: Use uapi/unistd.h to fix build error
  tools: Pass the target in descend
  tools: Honour the O= flag when tool build called from a higher Makefile
  tools: Define a Makefile function to do subdir processing
  x86: Export asm/{svm.h,vmx.h,perf_regs.h}
  perf tools: Fix strbuf_addf() when the buffer needs to grow
  perf header: Fix numa topology printing
  perf, powerpc: Fix hw breakpoints returning -ENOSPC
2012-12-01 13:07:48 -08:00
Darren Hart
aa10990e02 futex: avoid wake_futex() for a PI futex_q
Dave Jones reported a bug with futex_lock_pi() that his trinity test
exposed.  Sometime between queue_me() and taking the q.lock_ptr, the
lock_ptr became NULL, resulting in a crash.

While futex_wake() is careful to not call wake_futex() on futex_q's with
a pi_state or an rt_waiter (which are either waiting for a
futex_unlock_pi() or a PI futex_requeue()), futex_wake_op() and
futex_requeue() do not perform the same test.

Update futex_wake_op() and futex_requeue() to test for q.pi_state and
q.rt_waiter and abort with -EINVAL if detected.  To ensure any future
breakage is caught, add a WARN() to wake_futex() if the same condition
is true.

This fix has seen 3 hours of testing with "trinity -c futex" on an
x86_64 VM with 4 CPUS.

[akpm@linux-foundation.org: tidy up the WARN()]
Signed-off-by: Darren Hart <dvhart@linux.intel.com>
Reported-by: Dave Jones <davej@redat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: John Kacur <jkacur@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-11-26 17:41:24 -08:00
Chuansheng Liu
8ffeb9b0e6 watchdog: using u64 in get_sample_period()
In get_sample_period(), unsigned long is not enough:

  watchdog_thresh * 2 * (NSEC_PER_SEC / 5)

case1:
  watchdog_thresh is 10 by default, the sample value will be: 0xEE6B2800

case2:
 set watchdog_thresh is 20, the sample value will be: 0x1 DCD6 5000

In case2, we need use u64 to express the sample period.  Otherwise,
changing the threshold thru proc often can not be successful.

Signed-off-by: liu chuansheng <chuansheng.liu@intel.com>
Acked-by: Don Zickus <dzickus@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-11-26 17:41:24 -08:00
Linus Torvalds
b0db954c04 Merge branch 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull futex fix from Thomas Gleixner:
 "Single fix for a long standing futex race when taking over a futex
  whose owner died.  You can end up with two owners, which violates
  quite some rules."

* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  futex: Handle futex_pi OWNER_DIED take over correctly
2012-11-12 17:02:21 -08:00
Thomas Gleixner
59fa624519 futex: Handle futex_pi OWNER_DIED take over correctly
Siddhesh analyzed a failure in the take over of pi futexes in case the
owner died and provided a workaround.
See: http://sourceware.org/bugzilla/show_bug.cgi?id=14076

The detailed problem analysis shows:

Futex F is initialized with PTHREAD_PRIO_INHERIT and
PTHREAD_MUTEX_ROBUST_NP attributes.

T1 lock_futex_pi(F);

T2 lock_futex_pi(F);
   --> T2 blocks on the futex and creates pi_state which is associated
       to T1.

T1 exits
   --> exit_robust_list() runs
       --> Futex F userspace value TID field is set to 0 and
           FUTEX_OWNER_DIED bit is set.

T3 lock_futex_pi(F);
   --> Succeeds due to the check for F's userspace TID field == 0
   --> Claims ownership of the futex and sets its own TID into the
       userspace TID field of futex F
   --> returns to user space

T1 --> exit_pi_state_list()
       --> Transfers pi_state to waiter T2 and wakes T2 via
       	   rt_mutex_unlock(&pi_state->mutex)

T2 --> acquires pi_state->mutex and gains real ownership of the
       pi_state
   --> Claims ownership of the futex and sets its own TID into the
       userspace TID field of futex F
   --> returns to user space

T3 --> observes inconsistent state

This problem is independent of UP/SMP, preemptible/non preemptible
kernels, or process shared vs. private. The only difference is that
certain configurations are more likely to expose it.

So as Siddhesh correctly analyzed the following check in
futex_lock_pi_atomic() is the culprit:

	if (unlikely(ownerdied || !(curval & FUTEX_TID_MASK))) {

We check the userspace value for a TID value of 0 and take over the
futex unconditionally if that's true.

AFAICT this check is there as it is correct for a different corner
case of futexes: the WAITERS bit became stale.

Now the proposed change

-	if (unlikely(ownerdied || !(curval & FUTEX_TID_MASK))) {
+       if (unlikely(ownerdied ||
+                       !(curval & (FUTEX_TID_MASK | FUTEX_WAITERS)))) {

solves the problem, but it's not obvious why and it wreckages the
"stale WAITERS bit" case.

What happens is, that due to the WAITERS bit being set (T2 is blocked
on that futex) it enforces T3 to go through lookup_pi_state(), which
in the above case returns an existing pi_state and therefor forces T3
to legitimately fight with T2 over the ownership of the pi_state (via
pi_state->mutex). Probelm solved!

Though that does not work for the "WAITERS bit is stale" problem
because if lookup_pi_state() does not find existing pi_state it
returns -ERSCH (due to TID == 0) which causes futex_lock_pi() to
return -ESRCH to user space because the OWNER_DIED bit is not set.

Now there is a different solution to that problem. Do not look at the
user space value at all and enforce a lookup of possibly available
pi_state. If pi_state can be found, then the new incoming locker T3
blocks on that pi_state and legitimately races with T2 to acquire the
rt_mutex and the pi_state and therefor the proper ownership of the
user space futex.

lookup_pi_state() has the correct order of checks. It first tries to
find a pi_state associated with the user space futex and only if that
fails it checks for futex TID value = 0. If no pi_state is available
nothing can create new state at that point because this happens with
the hash bucket lock held.

So the above scenario changes to:

T1 lock_futex_pi(F);

T2 lock_futex_pi(F);
   --> T2 blocks on the futex and creates pi_state which is associated
       to T1.

T1 exits
   --> exit_robust_list() runs
       --> Futex F userspace value TID field is set to 0 and
           FUTEX_OWNER_DIED bit is set.

T3 lock_futex_pi(F);
   --> Finds pi_state and blocks on pi_state->rt_mutex

T1 --> exit_pi_state_list()
       --> Transfers pi_state to waiter T2 and wakes it via
       	   rt_mutex_unlock(&pi_state->mutex)

T2 --> acquires pi_state->mutex and gains ownership of the pi_state
   --> Claims ownership of the futex and sets its own TID into the
       userspace TID field of futex F
   --> returns to user space

This covers all gazillion points on which T3 might come in between
T1's exit_robust_list() clearing the TID field and T2 fixing it up. It
also solves the "WAITERS bit stale" problem by forcing the take over.

Another benefit of changing the code this way is that it makes it less
dependent on untrusted user space values and therefor minimizes the
possible wreckage which might be inflicted.

As usual after staring for too long at the futex code my brain hurts
so much that I really want to ditch that whole optimization of
avoiding the syscall for the non contended case for PI futexes and rip
out the maze of corner case handling code. Unfortunately we can't as
user space relies on that existing behaviour, but at least thinking
about it helps me to preserve my mental sanity. Maybe we should
nevertheless :)

Reported-and-tested-by: Siddhesh Poyarekar <siddhesh.poyarekar@gmail.com>
Link: http://lkml.kernel.org/r/alpine.LFD.2.02.1210232138540.2756@ionos
Acked-by: Darren Hart <dvhart@linux.intel.com>
Cc: stable@vger.kernel.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2012-11-01 12:06:54 +01:00
Rusty Russell
59ef28b1f1 module: fix out-by-one error in kallsyms
Masaki found and patched a kallsyms issue: the last symbol in a
module's symtab wasn't transferred.  This is because we manually copy
the zero'th entry (which is always empty) then copy the rest in a loop
starting at 1, though from src[0].  His fix was minimal, I prefer to
rewrite the loops in more standard form.

There are two loops: one to get the size, and one to copy.  Make these
identical: always count entry 0 and any defined symbol in an allocated
non-init section.

This bug exists since the following commit was introduced.
   module: reduce symbol table for loaded modules (v2)
   commit: 4a4962263f

LKML: http://lkml.org/lkml/2012/10/24/27
Reported-by: Masaki Kimura <masaki.kimura.kz@hitachi.com>
Cc: stable@kernel.org
2012-10-31 13:56:37 +10:30
Michael Neuling
0d855354ea perf, powerpc: Fix hw breakpoints returning -ENOSPC
I've been trying to get hardware breakpoints with perf to work
on POWER7 but I'm getting the following:

  % perf record -e mem:0x10000000 true

    Error: sys_perf_event_open() syscall returned with 28 (No space left on device).  /bin/dmesg may provide additional information.

    Fatal: No CONFIG_PERF_EVENTS=y kernel support configured?

  true: Terminated

(FWIW adding -a and it works fine)

Debugging it seems that __reserve_bp_slot() is returning ENOSPC
because it thinks there are no free breakpoint slots on this
CPU.

I have a 2 CPUs, so perf userspace is doing two perf_event_open
syscalls to add a counter to each CPU [1].  The first syscall
succeeds but the second is failing.

On this second syscall, fetch_bp_busy_slots() sets slots.pinned
to be 1, despite there being no breakpoint on this CPU.  This is
because the call the task_bp_pinned, checks all CPUs, rather
than just the current CPU. POWER7 only has one hardware
breakpoint per CPU (ie. HBP_NUM=1), so we return ENOSPC.

The following patch fixes this by checking the associated CPU
for each breakpoint in task_bp_pinned.  I'm not familiar with
this code, so it's provided as a reference to the above issue.

Signed-off-by: Michael Neuling <mikey@neuling.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Michael Ellerman <michael@ellerman.id.au>
Cc: Jovi Zhang <bookjovi@gmail.com>
Cc: K Prasad <prasad@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/1351268936-2956-1-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2012-10-30 10:07:58 +01:00
Linus Torvalds
2ab3f29ddd Merge branch 'akpm' (Andrew's fixes)
Merge misc fixes from Andrew Morton:
 "18 total.  15 fixes and some updates to a device_cgroup patchset which
  bring it up to date with the version which I should have merged in the
  first place."

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (18 patches)
  fs/compat_ioctl.c: VIDEO_SET_SPU_PALETTE missing error check
  gen_init_cpio: avoid stack overflow when expanding
  drivers/rtc/rtc-imxdi.c: add missing spin lock initialization
  mm, numa: avoid setting zone_reclaim_mode unless a node is sufficiently distant
  pidns: limit the nesting depth of pid namespaces
  drivers/dma/dw_dmac: make driver's endianness configurable
  mm/mmu_notifier: allocate mmu_notifier in advance
  tools/testing/selftests/epoll/test_epoll.c: fix build
  UAPI: fix tools/vm/page-types.c
  mm/page_alloc.c:alloc_contig_range(): return early for err path
  rbtree: include linux/compiler.h for definition of __always_inline
  genalloc: stop crashing the system when destroying a pool
  backlight: ili9320: add missing SPI dependency
  device_cgroup: add proper checking when changing default behavior
  device_cgroup: stop using simple_strtoul()
  device_cgroup: rename deny_all to behavior
  cgroup: fix invalid rcu dereference
  mm: fix XFS oops due to dirty pages without buffers on s390
2012-10-25 16:05:57 -07:00
H. Peter Anvin
2008713c71 Makefile: Documentation for external tool should be correct
If one includes documentation for an external tool, it should be
correct.  This is not:

1. Overriding the input to rngd should typically be neither
   necessary nor desired.  This is especially so since newer
   versions of rngd support a number of different *types* of sources.
2. The default kernel-exported device is called /dev/hwrng not
   /dev/hwrandom nor /dev/hw_random (both of which were used in the
   past; however, kernel and udev seem to have converged on
   /dev/hwrng.)

Overall it is better if the documentation for rngd is kept with rngd
rather than in a kernel Makefile.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Jeff Garzik <jgarzik@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-10-25 16:00:53 -07:00
Andrew Vagin
f230250577 pidns: limit the nesting depth of pid namespaces
'struct pid' is a "variable sized struct" - a header with an array of
upids at the end.

The size of the array depends on a level (depth) of pid namespaces.  Now a
level of pidns is not limited, so 'struct pid' can be more than one page.

Looks reasonable, that it should be less than a page.  MAX_PIS_NS_LEVEL is
not calculated from PAGE_SIZE, because in this case it depends on
architectures, config options and it will be reduced, if someone adds a
new fields in struct pid or struct upid.

I suggest to set MAX_PIS_NS_LEVEL = 32, because it saves ability to expand
"struct pid" and it's more than enough for all known for me use-cases.
When someone finds a reasonable use case, we can add a config option or a
sysctl parameter.

In addition it will reduce the effect of another problem, when we have
many nested namespaces and the oldest one starts dying.
zap_pid_ns_processe will be called for each namespace and find_vpid will
be called for each process in a namespace.  find_vpid will be called
minimum max_level^2 / 2 times.  The reason of that is that when we found a
bit in pidmap, we can't determine this pidns is top for this process or it
isn't.

vpid is a heavy operation, so a fork bomb, which create many nested
namespace, can make a system inaccessible for a long time.  For example my
system becomes inaccessible for a few minutes with 4000 processes.

[akpm@linux-foundation.org: return -EINVAL in response to excessive nesting, not -ENOMEM]
Signed-off-by: Andrew Vagin <avagin@openvz.org>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-10-25 14:37:53 -07:00
Linus Torvalds
cbb525b447 Merge branch 'for-3.7-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup fixes from Tejun Heo:
 "This pull request contains three fixes.

  Two are reverts of task_lock() removal in cgroup fork path.  The
  optimizations incorrectly assumed that threadgroup_lock can protect
  process forks (as opposed to thread creations) too.  Further cleanup
  of cgroup fork path is scheduled.

  The third fixes cgroup emptiness notification loss."

* 'for-3.7-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  Revert "cgroup: Remove task_lock() from cgroup_post_fork()"
  Revert "cgroup: Drop task_lock(parent) on cgroup_fork()"
  cgroup: notify_on_release may not be triggered in some cases
2012-10-24 16:35:13 -07:00
Linus Torvalds
d579a35d0e Merge branch 'for-3.7-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq
Pull workqueue fix from Tejun Heo:
 "This pull request contains one patch from Dan Magenheimer to fix
  cancel_delayed_work() regression introduced by its reimplementation
  using try_to_grab_pending().  The reimplementation made it incorrectly
  return %true when the work item is idle.

  There aren't too many consumers of the return value but it broke at
  least ramster."

* 'for-3.7-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
  workqueue: cancel_delayed_work() should return %false if work item is idle
2012-10-24 16:33:22 -07:00
Dan Magenheimer
c0158ca64d workqueue: cancel_delayed_work() should return %false if work item is idle
57b30ae77b ("workqueue: reimplement cancel_delayed_work() using
try_to_grab_pending()") made cancel_delayed_work() always return %true
unless someone else is also trying to cancel the work item, which is
broken - if the target work item is idle, the return value should be
%false.

try_to_grab_pending() indicates that the target work item was idle by
zero return value.  Use it for return.  Note that this brings
cancel_delayed_work() in line with __cancel_work_timer() in return
value handling.

Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
LKML-Reference: <444a6439-b1a4-4740-9e7e-bc37267cfe73@default>
2012-10-24 12:38:16 -07:00
Linus Torvalds
e17b131583 Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull perf fixes from Ingo Molnar:
 "Most of these are uprobes race fixes from Oleg, and their preparatory
  cleanups.  (It's larger than what I'd normally send for an -rc kernel,
  but they looked significant enough to not delay them.)

  There's also an oprofile fix and an uncore PMU fix."

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (22 commits)
  perf/x86: Disable uncore on virtualized CPUs
  oprofile, x86: Fix wrapping bug in op_x86_get_ctrl()
  ring-buffer: Check for uninitialized cpu buffer before resizing
  uprobes: Fix the racy uprobe->flags manipulation
  uprobes: Fix prepare_uprobe() race with itself
  uprobes: Introduce prepare_uprobe()
  uprobes: Fix handle_swbp() vs unregister() + register() race
  uprobes: Do not delete uprobe if uprobe_unregister() fails
  uprobes: Don't return success if alloc_uprobe() fails
  uprobes/x86: Only rep+nop can be emulated correctly
  uprobes: Simplify is_swbp_at_addr(), remove stale comments
  uprobes: Kill set_orig_insn()->is_swbp_at_addr()
  uprobes: Introduce copy_opcode(), kill read_opcode()
  uprobes: Kill set_swbp()->is_swbp_at_addr()
  uprobes: Restrict valid_vma(false) to skip VM_SHARED vmas
  uprobes: Change valid_vma() to demand VM_MAYEXEC rather than VM_EXEC
  uprobes: Change write_opcode() to use FOLL_FORCE
  uprobes: Move clear_thread_flag(TIF_UPROBE) to uprobe_notify_resume()
  uprobes: Kill UTASK_BP_HIT state
  uprobes: Fix UPROBE_SKIP_SSTEP checks in handle_swbp()
  ...
2012-10-24 04:07:51 +03:00